Outokumpu VDM high-temperature nickel alloys or titanium have been an important success factor for the international aviation industry for decades. The development of nickel alloys, titanium grades and titanium alloys is closely linked to aviation. The gas turbine with its peripheral components constitutes the most important application field for superalloys and the driving force in their development. Nickel alloys contribute decisively to an aircraft's efficiency, especially in the area of engine construction. In medium and high-pressure compressors, where high strength and high-temperature resistance are essential, semi-finished products such as bars, discs, plates, vanes and forgings are all used.
Most superalloys contain nickel or cobalt as their main alloy constituent. Stability at high temperatures, high creep strength, good fatigue behaviour, slow crack propagation, toughness and resistance to high-temperature oxidation are therefore the critical properties and features of superalloys.
In many cases, superalloys are remelted twice after primary melting, to ensure they fulfil the extremely stringent aerospace quality specifications in terms of purity, a homogeneous microstructure and exact chemical analysis.
Some components, for which low weight is equally important as high strength, are manufactured from titanium alloys. They are purpose-developed to demonstrate their extraordinary strength and corrosion resistance under high and critical stresses.
Besides alpha-beta alloys, for example VDM® Ti 6-4 (LT 31), commercially pure titanium grades such as VDM® Ti Grade 1 (RT 12), VDM® Ti Grade 2 (RT 15) und VDM® Ti Grade 3 (RT 18) are used in aviation applications in the form of semi-finished products such as bars, rods, plates and sheets. The outstanding combination of titanium's technological properties makes these materials indispensable for today's – and tomorrow's - aircraft. They ensure low weight, high strength, temperature stability, low susceptibility to fatigue, and high resistance to fracture and corrosion.
For large structural components such as vertical stabilizers, carbon fiber reinforced plastics (CFRP) are being used to an ever increasing extent. With an expansion coefficient one-eighth that of steel, the iron-nickel alloy VDM® Alloy 36 (Pernifer 36 – material no. 1.3912) fulfils the requirements specified for the moulds employed for curing the CFRP components.
The technological demands placed on high-performance materials for stationary turbines are comparable to those specified for aircraft engines. Here too, the special properties of nickel alloys are needed to ensure safe control of the process and the highest possible efficiency of the equipment. VDM® Alloy 617 (Nicrofer 5520 Co) and VDM® Alloy 75 (Nicrofer 7520) are used particularly for various components in stationary gas turbines. This includes combustion chambers, ring blanks, sealing components and internals, but also the transition zone from the combustion chamber to the turbine.